The bank holdup began in the usual way. Around 9:45 a.m., four men, at least two of them armed with handguns, strolled into the First National Bank of Southern Maryland at 4283 Branch Ave. in Marlow Heights. Minutes later, they emerged with a big full of money.

Outside the bank, they first encountered Edward Albert Poe, a 33-year-old shopping guard, and off-duty prince George's police Sgt. Terry Putman.

Putman fired three shots at one fleeing suspect, shattering the side window of his getaway car, which was later found abandoned several blocks away. Poe was injured in the crossfire and was reported in satisfactory condition yesterday afternoon at Greater Southeast Community Hospital.

Putman, meanwhile, apprehended another suspect fleeing on foot behind the bank. Then three officers from the District's fugitive squad passing by in an unmarked car spotted two other fleeing men, one of whom was carrying the bag.

Unknown to the holdup men, the money bag contained a special anticrime device. As they crossed the parking lot the bag exploded, spewing red dye and paper currency all over.

The D.C. police captured one of the suspects and District and prince George's County officers who converged on the scene found the other hiding behind some bushes.

Late yesterday, one suspect remained at large.